Hybrid photocatalysts using graphitic carbon nitride/cadmium sulfide/reduced graphene oxide (g-C3N4/CdS/RGO) for superior photodegradation of organic pollutants under UV and visible light

Abstract

Graphitic carbon nitride (g-C₃N₄) was hybridized with CdS nanoparticles and reduced graphene oxide (RGO) sheets using a facile chemical method, for the application of catalytic photodegradation of Rhodamine B and Congo red dyes under irradiation with UV and visible light. Fourier-transform infrared (FTIR) spectroscopy and X-ray photoemission spectroscopy (XPS) analyses confirmed the formation of pure g-C₃N₄, as well as g-C₃N₄/CdS, g-C₃N₄/RGO, and g-C₃N₄/CdS/RGO composites. The large surface area of the g-C₃N₄/CdS/RGO composite (70.42 m² g⁻¹) resulted in rapid dye adsorption onto the surface of the photocatalyst, leading to effective photodegradation of organic pollutants. The addition of CdS and RGO increased the photocatalytic activity of g-C₃N₄ by a factor of approximately twenty compared with that of the commercially available TiO₂ catalyst under visible light, and the g-C₃N₄/CdS/RGO composite was found to significantly enhance the catalytic effect compared with pure g-C₃N₄ and with the g-C₃N₄/CdS and g-C₃N₄/RGO composites. The superior photocatalytic activity of the g-C₃N₄/CdS/RGO composite is attributed to enhanced separation of the photogenerated electron–hole pairs, as well as increased visible-light absorption. The improved transport of photoelectrons was consistent with the results of transient photocurrent measurements. Therefore, g-C₃N₄/CdS/RGO composites using a facile method are applicable to the development of high-efficiency photocatalytic devices for industrial applications.